What is group B strep?
Group B streptococcus, or group B strep for short, is a certain kind of bacteria (germ) that lives in the intestine, rectum, and vagina (in women). Group B strep doesn’t usually cause problems in healthy adults. Most of the people who get sick from group B strep are newborns who are exposed to the bacteria during birth.
About 25% of healthy pregnant women have group B strep. A woman who has group B strep is said to be "colonized" with this germ. If you are colonized with group B strep, your baby can become infected with these germs while being born and can get sick. There is less than a 1% chance that this will happen, but because group B strep infection is so dangerous for babies, it's important to find out if you're colonized while you're pregnant.
Written by familydoctor.org editorial staff